Team gold medallist, Lee Nayoung defeated team-mate, Lee Yeonji in her opening match, 262-212 to take an early lead. Ishimoto knocked down the second best score of 254 to beat her team-mate, Yuri Sato to trail the Korean by 8 pins.
2017 South-East Asian Games Team silver medallist, Daphne Tan of Singapore rolled the third best game of 252 but had to content with fourth, behind Lara Posadas of Philippines, who won her match with 247.
Trios silver and Team bronze medallist, Chou Chia-Chen won her second match with a sizzling 267 after losing her opening match with 234 to take over the running. Singapore's Yeo won her first and second matches to move into second spot.
Lee slipped down to third after failing to win her second match despite knocking down 235. Although Ishimoto won her second match with 229, the Japanese dropped two spots down to fourth. But Ishimoto bounced back with a 247 victory in her third match to become the new leader.